Shovelhead Shuts Down When Hot

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  • HogsRear
    Member
    • Sep 2015
    • 71

    Shovelhead Shuts Down When Hot

    Looking for some ideas as to what could be happening with my bike now. It's a '73 Super Glide in a hardtail frame, ratchet top trans, Super E carb, kick only. It starts right up in one or two kicks very time when cold, then after about 20 minutes of riding starts to misfire and pop out of the exhaust. It gradually gets worse and worse until the bike just shuts down and will not start again until it has had some time to cool.

    So far I have put a new coil on, new points and condenser, plugs and plug wires, checked and redone timing, checked pushrods, new battery a few months ago, but the problem is still there. I recently switched to the Super E from a CV after the same problem thinking it might have been the culprit, but the bike seems to like the E better when it's running so I kept it. Put new intake O rings on when I changed carbs. The wiring was redone a few months ago when the bike was put together in the hardtailed frame. I've been digging through other threads with similar issues and have found a similar story being solved by replacing the advance unit and weights which I am going to try next. I have not had any engine work done since owning this bike and am unsure of the history behind it. I also haven't changed the regulator. Could the problem be related to the engine itself? Regulator? Battery? Any input or ideas are appreciated.
  • BuddhahoodVato
    Senior Member
    • Apr 2010
    • 2469

    #2
    Short

    Comment

    • Tattooo
      Senior Member
      • Sep 2012
      • 12407

      #3
      Weak battery...........

      Comment

      • JBinNC
        Senior Member
        • Dec 2018
        • 2713

        #4
        Originally posted by BuddhahoodVato
        Short
        Ding ding ding. ^^^

        Wire in the harness shorting through the insulation when hot. It happens. I just fixed (I hope) a similar problem. Harness at the handlebar switches ('96 - up style) were pinched where they should not have been. Ran perfectly until fully hot, about a half hour.

        Jim

        Comment

        • HogsRear
          Member
          • Sep 2015
          • 71

          #5
          Originally posted by Tattooo
          Weak battery...........
          A weak battery would fire right up fine then cause these symptoms after riding for a bit?

          Comment

          • HogsRear
            Member
            • Sep 2015
            • 71

            #6
            Originally posted by JBinNC
            Ding ding ding. ^^^

            Wire in the harness shorting through the insulation when hot. It happens. I just fixed (I hope) a similar problem. Harness at the handlebar switches ('96 - up style) were pinched where they should not have been. Ran perfectly until fully hot, about a half hour.

            Jim
            Thanks Jim. I will take a look through the whole harness asap and check for shorts.

            Comment

            • HogsRear
              Member
              • Sep 2015
              • 71

              #7
              Another thought related to that – if it were a short, wouldn't this cause the bike to immediately shut off rather than a slow decrease in performance, misfiring and popping over the span of a few minutes ultimately leading to a shut down?

              Comment

              • ncmc47
                Senior Member
                • Oct 2012
                • 132

                #8
                Could be a condenser getting ready to let go. Just because they're new doesn't mean they're good, they can break down on the shelf.

                Comment

                • Tattooo
                  Senior Member
                  • Sep 2012
                  • 12407

                  #9
                  Originally posted by HogsRear
                  A weak battery would fire right up fine then cause these symptoms after riding for a bit?
                  Damn right it will........ Especially on a kick bike with points..................

                  Comment

                  • metalheart28
                    Senior Member
                    • Feb 2014
                    • 631

                    #10
                    Is your tank vent plugged?

                    Comment

                    • HogsRear
                      Member
                      • Sep 2015
                      • 71

                      #11
                      Originally posted by metalheart28
                      Is your tank vent plugged?
                      Tank vent seems to be working fine, no difference in performance with gas cap off while running

                      Comment

                      • Micromark
                        Member
                        • Jul 2019
                        • 31

                        #12
                        Originally posted by Tattooo
                        Weak battery...........
                        I just experienced this. I run a Dynatek S though.... Bike ran great on the highway but once I got into town it would sputter and backfire. Let it sit for 10 minutes and kicked right over again only to start running bad again in a minute or so. Wouldn’t start a third time though.
                        Had a bad AGM battery.

                        Comment

                        • Tattooo
                          Senior Member
                          • Sep 2012
                          • 12407

                          #13
                          Originally posted by Micromark
                          Wouldn’t start a third time though. Had a bad AGM battery.
                          It's astounding what problems a weak battery will cause......

                          Comment

                          • HogsRear
                            Member
                            • Sep 2015
                            • 71

                            #14
                            Alright I have ordered a new sealed battery to replace the current lead acid battery I got from NAPA, hoping that it helps. Going to look over the wiring this weekend and see if there are any weak spots or pinched wires. Thanks all!

                            Comment

                            • Tattooo
                              Senior Member
                              • Sep 2012
                              • 12407

                              #15
                              Originally posted by HogsRear
                              Alright I have ordered a new sealed battery to replace the current lead acid battery
                              Did you happen to check it to see if it was bad???????????? Or are you just going to assume it's bad??????

                              Comment

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